{"id":"F2006B08620","name":"AD/CL-600/57 - Horizontal Stabilizer Trim Actuator","slug":"ad-cl-600-57-horizontal-stabilizer-trim-actuator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51579,"registerId":"commonwealth-F2006B08620-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nBombardier (Canadair) CL-600 (Challenger) Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/CL-600/57 Horizontal Stabilizer Trim ","sectionType":"part","heading":"AD/CL-600/57 Horizontal Stabilizer Trim Actuator 7/2002","content":"# AD/CL-600/57 Horizontal Stabilizer Trim Actuator 7/2002\n\nApplicability: CL-600-2B19 Canadair Regional Jet (CRJ) aircraft fitted with horizontal stabilizer trim actuator (HSTA) Part Number (PN) 601R92305-1 or PN 601R92305-3.\n\nRequirement: Unless previously accomplished:\n\n    Revise the approved maintenance schedule to incorporate Temporary Revision (TR) No. 2B-816 dated 28 November 2001, Part 2 of the Maintenance Requirements Manual, Appendix B- Limitations.\n    Replace the horizontal stabilizer trim actuator.\n\nNote: Canadian AD CF-2002-20 refers.\n\nCompliance: Unless previously accomplished:\n\n    For Requirement 1, within 14 days from the effective date of this Directive\n\n    2. For Requirement 2:\n\n    Before 19,200 hours actuator time in service (TIS), or\n\n    b. For HSTA’s exceeding 19,200 hours TIS and those HSTA’s which will exceed 19,200 hours TIS within 500 hours TIS from the effective date of this Directive; replace within 500 hours TIS.\n\nThis Airworthiness Directive becomes effective on 11 July 2002.\n\nBackground: Endurance testing of the HSTA has identified that a life limit is required to prevent failure of key components within the HSTA.\n\n![Signature of James Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 23 May 2002\n\n![](image.001.png)","sortOrder":1}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — addressing a specific mechanical wear issue in identified aircraft components. The scope has not expanded beyond the original safety purpose of preventing HSTA failure through life limits and replacement requirements."},"complexity_factors":["Single, clearly defined applicability (two specific part numbers on one aircraft series)","Only two substantive requirements with straightforward compliance deadlines","Minimal cross-referencing (single reference to Canadian AD CF-2002-20)","No nested exceptions or conditional logic beyond simple time-based thresholds","Short document (approximately 250 words excluding headers and images)","Only one defined term used (TIS - Time In Service, clarified in context)"],"plain_english_summary":"Australia’s aviation safety order applies to Bombardier CRJ jets with certain horizontal stabilizer trim actuators (HSTAs). CASA requires operators to update maintenance records within 14 days to reflect new life limits and to replace affected actuators before 19,200 flight hours (or within 500 hours if near that limit). It targets airlines and maintenance organizations to prevent actuator wear that could cause loss of control."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD implements a targeted safety action — establishing a life limit for a specific horizontal stabilizer trim actuator and requiring maintenance‑manual revision and replacement by specified hours‑in‑service. That is consistent with the AD's stated original purpose (correcting an unsafe condition identified by endurance testing). The instrument does not materially broaden scope beyond imposing that life limit and the associated maintenance actions on the specified part numbers and aircraft."},"complexity_factors":["Short, single‑subject Airworthiness Directive (two required actions only)","Limited conditional logic (two time/usage thresholds for replacement: <19,200 hours vs >19,200 or within 500 hours of exceeding)","Cross‑references to external documents: Temporary Revision No. 2B‑816, Canadian AD CF‑2002‑20, and CAR 1998 subreg 39.1(1)","Straightforward applicability (two specific part numbers) with no nested exceptions","Compliance deadlines are explicit (14 days; 500 hours) which reduces interpretive complexity"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Applies to: Bombardier (Canadair) CL-600-2B19 (CRJ) aircraft that have a horizontal stabilizer trim actuator (HSTA) with part number 601R92305-1 or 601R92305-3 (Applicability).\n- Requires two things (Requirement):\n  1. Update the aircraft's approved maintenance schedule to include Temporary Revision No. 2B-816 (Part 2, Appendix B – Limitations). That revision contains the new life‑limit/maintenance limitations for the actuator.\n  2. Replace the specified HSTA units according to the hours‑in‑service limits set out in the AD.\n- Timing (Compliance):\n  - The maintenance‑schedule revision must be done within 14 days of the AD taking effect.\n  - Actuators must be replaced before they reach 19,200 hours time‑in‑service (TIS). If an actuator already exceeds 19,200 hours TIS or will exceed 19,200 hours within 500 hours of the AD's effective date, it must be replaced within 500 hours TIS.\n- Legal authority and effective date: The AD is issued by a CASA delegate under CAR 1998 subregulation 39.1(1) and became effective on 11 July 2002.\n\nWhy the instrument exists (stated reason)\n\n- The AD explains that endurance testing of the HSTA showed that a formal life limit is necessary to prevent failure of key internal components. The life limit and related maintenance action are intended to correct that unsafe condition.\n\nWho is affected and who pays\n\n- Directly affected: operators/owners of CL-600-2B19 aircraft fitted with the specified actuator part numbers; maintenance organisations responsible for those aircraft.\n- Who pays: aircraft operators (or their lessors) pay for the required maintenance manual update, the cost of replacing actuators, downtime while aircraft are out of service, and any logistics (shipping, inspection, record updates).\n\nPractical effects on behaviour and business\n\n- Operators must track actuator part numbers and cumulative actuator hours, update maintenance documentation quickly (within 14 days), and schedule replacements so no actuator exceeds the life limit.\n- Replacement creates demand for the approved HSTA replacement unit (and for associated labour). That shifts costs onto operators and may create short‑term supply or scheduling pressures for maintenance providers.\n\nTrade‑offs, compliance burden and implementation risk (mechanical testing of the policy claim)\n\n- Trade‑off: the AD exchanges operator cost and aircraft downtime for a reduced risk of actuator failure. The stated safety rationale is endurance testing evidence (Background).\n- Compliance burden: time‑sensitive paperwork (14‑day change), accurate tracking of TIS per actuator, and scheduling replacement within the hours‑limits. Operators need to confirm part numbers and historical hours records for each actuator.\n- Implementation risks: if replacement parts are constrained, operators may face aircraft groundings or need to source alternative approved parts; record‑keeping errors could lead to non‑compliance; small operators may be disproportionately affected if spares are limited.\n\nEffects on market players and competition\n\n- Manufacturers or approved distributors of replacement HSTAs benefit from increased demand. Independent maintenance organisations may see increased workload and revenue, but also face coordination and supply risks.\n- The AD limits operator choice about deferring replacement: it is a mandatory, time‑limited safety action issued by the regulator (Requirement and Compliance sections).\n\nWhere decision‑making sits\n\n- The action is required by a CASA delegate under subregulation 39.1(1) of CAR 1998. The regulator (through the delegate) decides the corrective action and compliance timing. Operators must follow the inspector/AD instructions and document compliance in maintenance records.\n\nKey references inside the AD: Applicability; Requirement (maintenance revision and replacement); Compliance (14 days for revision, 19,200 hours / 500 hours replacement windows); Background (endurance testing); reference to Canadian AD CF‑2002‑20 and Temporary Revision 2B‑816.\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-cl-600-57-horizontal-stabilizer-trim-actuator","history":"/api/acts/ad-cl-600-57-horizontal-stabilizer-trim-actuator/history","analysis":"/api/acts/ad-cl-600-57-horizontal-stabilizer-trim-actuator/analysis","conflicts":"/api/acts/ad-cl-600-57-horizontal-stabilizer-trim-actuator/conflicts","importantCases":"/api/acts/ad-cl-600-57-horizontal-stabilizer-trim-actuator/important-cases","documents":"/api/acts/ad-cl-600-57-horizontal-stabilizer-trim-actuator/documents"}}